Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Graphite is a known crystallographic form of carbon. A monolayer honeycomb structure of carbon atoms, known as graphene, has been considered thermodynamically unstable in free-standing form. Research efforts have studied graphene's electronic characteristics. Graphene appears to possess properties that may be advantageous in certain applications, for example, graphene appears to be chemically inert and appears to exhibit no absorption in the mid-infrared (IR) spectral range.
Graphene formation techniques include, for example, cleavage of Highly Oriented Pyrolytic Graphite (HOPG) followed by transfer of a few layers to a substrate, peeling off surface layers of HOPG using tape, and transferring the surface layers to a substrate by subsequent taping. Another graphene formation technique includes an exfoliation and Dry Contact Transfer (DCT) technique, which relies on transferring small crystallites from a stamp or a mold to a solid substrate. Graphene formation techniques have not been compatible with practical, large-scale production.